diff options
| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-04-27 15:21:52 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-05-08 11:07:32 +0200 |
| commit | 03335e95e27fc1f2b17b05b27342ad76986b3cf0 (patch) | |
| tree | 898f968c90a2db88bcbc82e7f972e9f0777b9e7c /arch | |
| parent | dde74f2e4a4447ef838c57e407f7139de3df68cb (diff) | |
x86/asm/entry/64: Clean up usage of TEST insns
By the nature of TEST operation, it is often possible
to test a narrower part of the operand:
"testl $3, mem" -> "testb $3, mem"
This results in shorter insns, because TEST insn has no
sign-entending byte-immediate forms unlike other ALU ops.
text data bss dec hex filename
11674 0 0 11674 2d9a entry_64.o.before
11658 0 0 11658 2d8a entry_64.o
Changes in object code:
- f7 84 24 88 00 00 00 03 00 00 00 testl $0x3,0x88(%rsp)
+ f6 84 24 88 00 00 00 03 testb $0x3,0x88(%rsp)
- f7 44 24 68 03 00 00 00 testl $0x3,0x68(%rsp)
+ f6 44 24 68 03 testb $0x3,0x68(%rsp)
- f7 84 24 90 00 00 00 03 00 00 00 testl $0x3,0x90(%rsp)
+ f6 84 24 90 00 00 00 03 testb $0x3,0x90(%rsp)
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1430140912-7960-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 8f8b22a361df..60705b032521 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -601,7 +601,7 @@ ENTRY(ret_from_fork) RESTORE_EXTRA_REGS - testl $3,CS(%rsp) # from kernel_thread? + testb $3, CS(%rsp) # from kernel_thread? /* * By the time we get here, we have no idea whether our pt_regs, @@ -665,7 +665,7 @@ END(irq_entries_start) leaq -RBP(%rsp),%rdi /* arg1 for \func (pointer to pt_regs) */ - testl $3, CS-RBP(%rsp) + testb $3, CS-RBP(%rsp) jz 1f SWAPGS 1: @@ -720,7 +720,7 @@ ret_from_intr: CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET RBP - testl $3,CS(%rsp) + testb $3, CS(%rsp) jz retint_kernel /* Interrupt came from user space */ @@ -968,7 +968,7 @@ ENTRY(\sym) .if \paranoid .if \paranoid == 1 CFI_REMEMBER_STATE - testl $3, CS(%rsp) /* If coming from userspace, switch */ + testb $3, CS(%rsp) /* If coming from userspace, switch */ jnz 1f /* stacks. */ .endif call paranoid_entry @@ -1309,7 +1309,7 @@ ENTRY(error_entry) SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 xorl %ebx,%ebx - testl $3,CS+8(%rsp) + testb $3, CS+8(%rsp) jz error_kernelspace error_swapgs: SWAPGS @@ -1606,7 +1606,6 @@ end_repeat_nmi: je 1f movq %r12, %cr2 1: - testl %ebx,%ebx /* swapgs needed? */ jnz nmi_restore nmi_swapgs: |